In nuclear reactors designed with passive operating systems, the laws of physics are employed to ensure that safe operation of the nuclear reactor is maintained during normal operation or even in an emergency condition without operator intervention or supervision, at least for some predefined period of time. A nuclear reactor 5 includes a reactor core 6 surrounded by a reactor vessel 2. Water 10 in the reactor vessel 2 surrounds the reactor core 6. The reactor core 6 is further located in a shroud 122 which surround the reactor core 6 about its sides. When the water 10 is heated by the reactor core 6 as a result of fission events, the water 10 is directed from the shroud 122 and out of a riser 124. This results in further water 10 being drawn into and heated by the reactor core 6 which draws yet more water 10 into the shroud 122. The water 10 that emerges from the riser 124 is cooled down and directed towards the annulus 123 and then returns to the bottom of the reactor vessel 2 through natural circulation. Pressurized steam 11 is produced in the reactor vessel 2 as the water 10 is heated.
A heat exchanger 135 circulates feedwater and steam in a secondary cooling system 130 in order to generate electricity with a turbine 132 and generator 134. The feedwater passes through the heat exchanger 135 and becomes super heated steam. The secondary cooling system 130 includes a condenser 136 and feedwater pump 138. The steam and feedwater in the secondary cooling system 130 are isolated from the water 10 in the reactor vessel 2, such that they are not allowed to mix or come into direct contact with each other. The secondary cooling system 130 may comprise piping 139 for transporting steam or feedwater.
The reactor vessel 2 is surrounded by a containment vessel 4. The containment vessel 4 is designed so that water or steam from the reactor vessel 2 is not allowed to escape into the surrounding environment. A steam valve 8 is provided to vent steam 11 from the reactor vessel 2 into an upper half 14 of the containment vessel 4. A submerged blowdown valve 18 is provided to release the water 10 into suppression pool 12 containing sub-cooled water.
Piping 139 and other connections are provided between the nuclear reactor 5 and the secondary cooling system 130 or other systems in the power generation facility. In the event of an earthquake or other seismic activity, significant forces or vibration may be transferred to, or by, the connections, which can place great stress on the connections. Forces resulting from thermal expansion also place stress on the connections. Maintaining integrity of these connections helps discourage the inadvertent release of radioactive or other materials from the various systems, and reduces maintenance or damage that might otherwise occur if one or more of the connections fail.
The present invention addresses these and other problems.